1. Field of the Invention
This invention concerns coal loading or batching apparatus and method for loading moving railroad cars with precise weights of coal, e.g., maximum car weight capacity, from large silos substantially positioned above railroad tracks, and particularly concerns such apparatus and method in the forms required for adapting existing coal silos and car loading sites to accommodate larger capacity cars and their maximum load capacities while providing markedly improved loading weight monitoring and regulation.
In order to achieve the high capacity car loading rates required by certain mining operations in the limited loading space allowed, while maintaining the loading accuracy required, it was necessary to design a unique system and method of operation, and to optimize every part of that system. For example, space limitations under certain silos of long standing allow the use of only two weigh bins, each having a capacity, e.g., of about 45 tons. Therefore, the only way to load a 100+ton rail car with two such 45 ton bins is to dump, reload and dump again at least one of the bins.
Such multiple charging and discharging operations, in order to be commercially efficient, must be done at a rate which can accommodate a railcar moving, e.g., about one mile/hr. Due to the necessity for such double operations for each car, adequate time may not be available for some loading sites and their available equipment for precisely preloading both bins such that a target weight, of e.g., 120 tons can be accurately achieved. Consequently, the present unique structures and operations which have been designed for two bins under each silo, employ bins of similar construction but which have different but complimentary functions and are differently operated, whereby a high target weight loading accuracy is achieved due to the fact that one of the bins is adapted to make full bin capacity discharges, while the other bin is adapted to make precise, topping weight discharges.
2. Discussion of Prior Art
Certain types of apparatus and methods presently in use for loading large railroad cars of, e.g., 100+ton capacity, typically involve dumping large loads of approximate desired weights into moving cars from silos, weigh bins, conveyors, or other loading equipment. The use of such apparatus and methods however, often leads to significant weight inaccuracies in filling the cars, e.g., by running of the cars past the loading apparatus' discharge point with consequent spillage of the coal over the rear of the cars, or by spillage over the silos of the car as a natural result of the high discharging rates required, or by inadequate material weighing facilities on the apparatus which allows loading the cars to weights which are not within prescribed limits set e.g., by Federal Regulations, or by the coal mining site, or by the MAP railroad operators.
Such apparatus and methods are exemplified in U.S. Pat. Nos. 4,460,308; 4,629,392; 4,284,380; 4,904,154; and 4,659,274, the disclosures of which are hereby incorporated herein in their entirety by reference. None of these disclosures however, speak to the problem of how to efficiently and precision load large, e.g., 120 ton capacity cars which must pass beneath huge preexisting coal silos which provide only limited space thereunder for car loading equipment employing weigh bins which lie intermediate the silo and the car.